1. Field of the Invention
The present invention relates to a liquid filled type vibration isolating device to be used for an engine mount of an automobile or the like.
2. Prior Art
In such a liquid filled type vibration isolating device as disclosed in JP-A 60-8540, a part of a wall of a liquid chamber is constituted by a first elastic wall to be deformed by the input vibration and a vibration plate vibrating in the opposite phase to that of the input vibration, and a part of a wall of a sub chamber is constituted by the above-mentioned vibration plate and a second elastic wall, and liquid is filled in the liquid chamber and the sub chamber.
In such a vibration isolating device, even at low frequency of the input vibration, liquid pressure of the liquid chamber acts on one surface of the vibration plate, and when the vibration of large amplitude is inputted, the liquid pressure of the liquid chamber becomes high or low and large force acts on one surface of the vibration plate. In order to vibrate the vibration plate against the large force by an actuator such as a solenoid, the strength of the vibration plate and the drive force of the actuator must be raised. If this necessity is satisfied, the vibration isolating device is increased in size, weight and power consumption, and therefore becomes large scale. Consequently, such a vibration isolating device can not be easily put into practice.